I dont like trade mechanics, it makes no sense the lack of gestioning the trade routes in a single menu, showing the trade posibilities for each city the posibility of modify the routes when desired and not every x turns, which i found disturbibg.
It makes no sense the decission of constructing the caravan in a city as an unit, but then allowing instant transportation to any city. It is difficult to see trade posibilities and is frustrating when you have almost 10 different routes, the constant popup to modify or renew each one.
To me they should be gestioned like spies, with a single menu showing trade posibilities and allowing to assign each caravan to the desired traderoute.
It could be easily implemented, just with one turn of waiting to move each caravan to the requested city (like spies) a period of waiting if a caravan is raided until a new one apeares (like spies) also introducing experience on caravans in the same way as spies and making trade routes auto renovable until the user allows to give new orders to the caravan.
The number of avaliable caravans can easily be gestiones like the number of diplomats, making then apear automatically after a certain condition is reach and so on.